What is the last non - zero digit in (20!)!? (That is, factorial of 20 factorial).

Humbug, using the FTOA, it is obvious the last non-zero digit of n! is the equivalent to that of n!/(10)^k (10=5*2 prime factors), use this fact for a large enough k to monkey it through your spreadsheet.

Posted by SatanClaus on 2003-12-21 14:55:07